The present invention relates generally to integrated circuits, and more particularly, to an integrated circuit fuse and method of opening a fuse.
Back-end-of-line (BEOL) modifications are common in integrated circuit (IC) manufacture. One mechanism for making changes to an IC is to open a fuse that has been built into the IC. One widely used approach to opening a fuse is using a laser to destroy a fuse wire. Laser blown fuses have the advantage of allowing only selected fuses to be blown without the use of a chrome-on-glass mask. In operation, an infrared laser is used to heat a element to the point where it is destroyed, opening the wiring path.
One disadvantage of this approach, however, is that the destruction of the element is explosive and oftentimes causes damage to surrounding materials, e.g., insulator. Conventionally, damage to surrounding materials is inadequate to harm the delicate wiring at lower levels, which could cause IC failure. In many newer applications, however, very large elements, e.g., wide and tall, are provided at the last level to accommodate better power distribution. Unfortunately, larger elements result in larger fuses that require more laser energy to open, and thus cause more damage to surrounding materials. Accordingly, there is now a higher risk of damage to the delicate wiring used at the lower levels and a higher risk of IC failure.
Another disadvantage of current fuse technology is the necessity to place the fuses in the last metal layer, which limits design possibilities.
In view of the foregoing, there is a need for a method of opening an IC fuse that does not damage surrounding areas, and allows for non-last metal layer positioning of the fuse.